An internal combustion engine generally combusts a fuel to produce mechanical power. Introduction of the fuel into a cylinder of the internal combustion engine is most commonly achieved using a fuel injector. A commonly used injector is a closed-nozzle injector which includes a nozzle assembly having a spring-biased needle valve element positioned adjacent an injector nozzle for allowing the fuel to be injected into the cylinder of the internal combustion engine. The needle valve element moves to allow the fuel to pass through the injector nozzle and out of injector orifices or spray holes, thus marking the beginning of a fuel injection event.
Fuel injectors typically provide a single injection profile based on structural characteristics of the fuel injector such as number of orifices, cross-section area of orifices etc. A change in functional requirement or an application area of the engine in which the fuel injector is being used may need variation in injection profile. Such variation typically may not be provided by a single fuel injector, and multiple fuel injectors may be required for providing different injection profiles.
German Patent Application Number DE 10200/4021538 describes a fluid flow control valve. The fluid flow control valve includes two coaxial valve needles. An inner needle is completely enclosed inside an outer needle. Flow of fuel to jets in the outer needle is blocked by the inner needle. Large diameter jets in the hollow conical nozzle body are provided in line with the jets in the outer needle. The outer needle blocks additional flow to jets in a conical nozzle. The inner and the outer needles together provide a set of injection openings to inject fuel into the combustion chamber.